"Tips" are male, entire sheep of any age, although those under a year may sometimes be referred to as "tip lambs". I've never heard the term used outside of Northern Ireland. On the Mainland UK they use "tups".

You're not far off with these guesses, you know! Females transition from lambs to hoggets at the start of the next breeding season. So my pet ewe lambs from 2016 became hoggets the moment a lamb was born in 2017, even though they were 9 months old at the time. They remain hoggets until the following breeding season, so in the case of Rosie and her friends, 2018, when they are two. Then they're just ewes.